On 14 September 2015, the Advanced Laser Interferometer Gravitational-wave Observatory (aLIGO) detected the first gravitational wave (GW) signal, dubbed GW150914.  Gravitational waves are 'ripples' in the fabric of space-time propagating through the Universe at the speed of light. The strongest GW signals are produced by catastrophic events such as colliding black holes, coalescing neutron stars or the gravitational collapse of very massive stars.  Some of these astrophysical phenomena also produce bright electromagnetic radiation such as GRBs and their afterglows, supernovae and kilonovae.  For this reason, astronomers are eager to observe the sky after a GW event is detected as they hope to catch the electromagnetic glow following the burst of GW radiation.

The aim of this project is to analyze the electromagnetic observations of GW150914. Your dataset will consist of Swift/XRT, and Swift/UVOT data. You are asked to produce 1) images, showing the observed fields, 2) a list of X-ray sources, their detection significance, and hardness ratio 3) a list of optical counterparts for each detected X-ray source, 4) upper limits for each observed XRT field.  In the labs you have already seen most of the steps required to complete this project, however, you will also be introduced to a few tools and techniques that are specific to this task.

Once you have completed your data reduction and analysis, you will compare your results with the LIGO observations, existing catalogs, and standard GRB afterglows. In particular, the following questions should be addressed:

·      what is the probability that each observed field includes the true GW location?

·      did Swift detect a new, uncatalogued source?

·      did any of the known sources show signs of variability?

·      can any of the detected sources be considered a possible counterpart of GW150914?

·      compare your upper limits with the typical brightness of a GRB afterglow. what conclusions can be drawn?

Your write up should consist of an abstract, an introduction, observations, analysis, and discussion section followed by a conclusion. Throughout the text include as many figures, tables, and equations as you see fit. Remember to properly cite all your references and include a thorough reference section at the end.

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One of the objectives of the project is to expose you to independent research. Thus, it is your responsibility to manage your time appropriately and perform the background reading required to complete the project on time. 

Collaboration is encouraged: collaborating with colleagues and bouncing ideas off each other is something we do regularly in our work. However, keep in mind that although your are permitted to collaborate during lab time, the write-up itself should be an entirely independent effort. 

The instructor will NOT accept manuscripts that contain even small portions that we consider unreasonably similar.

Role of the instructor

I will be available to answer questions during regular office and class hours, and to open up the lab outside of class time if needed.  I am not there to walk you through each step, rather I am there so you can use me as a resource of information that you would not be able to obtain on your own. I will however make sure that your are not stumped by the more complicated aspects of the project.